Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard, a trackball device, or the like. Via the keyboard, characters and symbols can be inputted into the computer system directly. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboards.
FIG. 1 is a schematic top view illustrating the outer appearance of a conventional keyboard. As shown in FIG. 1, there are plural keys 10 on a surface of the conventional keyboard 1. These keys 10 are classified into several types, e.g. ordinary keys 101, numeric keys 102 and function keys 103. When one of these keys 10 is depressed by the user's finger, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key. For example, when an ordinary key 101 is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key 102 is depressed, a corresponding number is inputted into the computer. In addition, the function keys 103 (F1˜F12) can be programmed to provide various functions. For example, the conventional keyboard 1 is a keyboard for a notebook computer.
With the maturity of the computing technologies, the keyboard manufacturers make efforts in designing novel keyboards with special functions in order to meet diversified requirements of different users. For this reason, luminous keyboards are favored by users. Hereinafter, the inner structure of the luminous keyboard will be illustrated in more details. FIG. 2 is a schematic cross-sectional view illustrating a conventional luminous keyboard. As shown in FIG. 2, the conventional luminous keyboard 2 comprises plural key structures 20, a membrane switch circuit member 21, a light guide plate 22, an illumination module 23, a supporting plate 24 and a reflecting plate 25. Each key structure 20 comprises a keycap 201, a scissors-type connecting element 202 and an elastic element 203. From top to bottom, the keycap 201, the scissors-type connecting element 202, the elastic element 203, the membrane switch circuit member 21, the supporting plate 24, the light guide plate 22 and the reflecting plate 25 of the conventional luminous keyboard 2 are sequentially shown. The supporting plate 24 is arranged between the membrane switch circuit member 21 and the light guide plate 22 for supporting the keycap 201, the scissors-type connecting element 202, the elastic element 203 and the membrane switch circuit member 21.
In the key structure 20, the keycap 201 is exposed outside the conventional luminous keyboard 2, so that the keycap 201 can be depressed by the user. The scissors-type connecting element 202 is used for connecting the keycap 201 and the supporting plate 24. The elastic element 203 is penetrated through the scissors-type connecting element 202. In addition, both ends of the elastic element 203 are contacted with the keycap 201 and the membrane switch circuit member 21, respectively. The membrane switch circuit member 21 comprises an upper wiring board 211, a separation layer 212, and a lower wiring board 213. The upper wiring board 211 comprises plural upper conductive parts 2111. The separation layer 212 is located under the upper wiring board 211. Moreover, the separation layer 212 comprises plural separation layer openings 2121 corresponding to the plural upper conductive parts 2111. The lower wiring board 213 is located under the separation layer 212. Moreover, the lower wiring board 213 comprises plural lower conductive parts 2131 corresponding to the plural upper conductive parts 2111. Moreover, plural key switches 214 are defined by the plural lower conductive parts 2131 and the plural upper conductive parts 2111 collaboratively. The upper wiring board 211, the separation layer 212 and the lower wiring board 213 are all made of a light-transmissible material. The light-transmissible material is for example polycarbonate (PC) or polyethylene (PE). Consequently, the upper wiring board 211, the separation layer 212 and the lower wiring board 213 are light-transmissible.
The illumination module 23 comprises an illumination circuit board 231 and plural light-emitting elements 232. For clarification and brevity, only two light-emitting elements 232 are shown in the drawing. The illumination circuit board 231 is located under the membrane switch circuit member 21 for providing electric power to the plural light-emitting elements 232. The plural light-emitting elements 232 are disposed on the illumination circuit board 231. In addition, the plural light-emitting elements 232 are inserted into plural reflecting plate openings 251 of the reflecting plate 25 and plural light guide plate openings 221 of the light guide plate 22, respectively. By acquiring the electric power, the plural light-emitting elements 232 are driven to emit plural light beams B. Moreover, the plural light beams B are introduced into the light guide plate 22. For example, the plural light-emitting elements 232 are side-view light emitting diodes. The light guide plate 22 is used for guiding the plural light beams B to the keycaps 201. The reflecting plate 25 is located under the light guide plate 22 for reflecting the plural light beams B. Consequently, the plural light beams B are directed upwardly, and the utilization efficiency of the light beams B is enhanced. The two lateral edges 252 of the reflecting plate 25 are bent upwardly to enclose plural lateral edges 222 of the light guide plate 22. For clarification and brevity, only one lateral edge 252 of the reflecting plate 25 is shown in the drawing. Due to the lateral edges 252 of the reflecting plate 25, the problem of causing light leakage through the lateral edges 222 of the light guide plate 22 will be eliminated.
In the conventional luminous keyboard 2, each keycap 201 has a light-outputting zone 2011. The light-outputting zone 2011 is located at a character region or a symbol region of the keycap 201. Moreover, the position of the light-outputting zone 2011 is aligned with the position of a corresponding light-guiding dot 223 of the light guide plate 22. The light beams can be guided upwardly to the light-outputting zone 2011 by the corresponding light-guiding dot 223. After the plural light beams B are transferred within the light guide plate 22 and projected on the light-guiding dots 223, the light beams B are guided by the light-guiding dots 223 and projected upwardly. The upwardly-projected portions of the light beams B are sequentially transmitted through plural supporting plate openings 241 of the supporting plate 24 and the membrane switch circuit member 21 and transmitted through the plural light-outputting zones 2011 of the keycaps 201 so as to illuminate the character regions or the symbol regions of the keycaps 201. Under this circumstance, the illuminating function is achieved.
However, the conventional luminous keyboard 2 still has some drawbacks. For example, all of the key structures of the luminous keyboard 2 are simultaneously illuminated. If the user intends to illuminate the key structure A but not illuminate the key structure B, the use of the luminous keyboard 2 cannot meet the user's requirement. For meeting the user's requirement, the luminous keyboard uses top-view light emitting diodes. That is, a single top-view light emitting diode is located under the keycap of one key structure. Since the illumination of each top-view light emitting diode is independently controlled, the use of the top-view light emitting diode can meet the user's requirement. The light beam emitted by the top-view light emitting diode is projected upwardly to the corresponding keycap. Since the light beam from the top-view light emitting diode is very centralized, the luminance uniformity is usually unsatisfied.
Therefore, there is a need of providing a luminous keyboard for controlling illumination of individual keys and producing enhanced luminance uniformity.